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Bug 363299

Summary:	[Xtend2] problem with type inference
Product:	[Modeling] TMF	Reporter:	Lieven Lemiengre <lieven.lemiengre>
Component:	Xtext	Assignee:	Project Inbox <tmf.xtext-inbox>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	normal
Priority:	P3	CC:	sebastian.zarnekow
Version:	2.1.0
Target Milestone:	---
Hardware:	PC
OS:	Windows 7
Whiteboard:

Description Lieven Lemiengre

2011-11-09 07:57:00 EST

problem:

class SomeSemanticHighlightingCalculator implements ISemanticHighlightingCalculator {
	
  override provideHighlightingFor(XtextResource resource, IHighlightedPositionAcceptor acceptor) {
    if(resource == null) return;
    val Iterator<EObject> iter = EcoreUtil2::getAllContents(resource, true)
    while(iter.hasNext) {
      highlight(iter.next, acceptor)
    }
  }
}

I have to explicitly type iter as 'Iterator<EObject>' otherwise the type 'Iterator<?>' is inferred.

Comment 1 Sebastian Zarnekow

2011-11-09 08:02:05 EST

This works as expected.

The signature of EcoreUtil.getAllContents looks like this:

<T> TreeIterator<T> getAllContents(Resource, boolean)

thus you'd have to use

Iterator<EObject> iter = EcoreUtil.<EObject>getAllContents(..) 

in Java where Xtend allows to use

val iter = EcoreUtil::<EObject>getAllContents(..)

or

val Iterator<EObject> iter = EcoreUtil::getAllContents(..)

Comment 2 Sebastian Zarnekow

2011-11-09 08:03:49 EST

(In reply to comment #1)
> you'd have to use
> 
> Iterator<EObject> iter = EcoreUtil.<EObject>getAllContents(..) 
> 
> in Java 

That was too fast. Java has inference for the type argument, too. E.g. the following is valid in Java and in Xtend:

Iterator<EObject> iter = EcoreUtil.getAllContents(..)